A proximity detector having a power switch 30 which is switched as a function of the approach of an object. The detector includes a MOS depletion transistor T1 which connects one of the terminals 15 of the detector to a control input of a power switch 30 through a control switch T2. A regulator stage 45 is coupled to T1 in order to keep T1 saturated in the closed condition of the detector and to regulate the gate voltage of T1 when the detector is in a open state.